Within the passenger compartment of a vehicle, many occupant restraint systems can be utilized, such as seatbelts and air bag systems. For instance, air bag systems can supplement the protection offered by seatbelts. Air bag systems typically comprise at least one folded air bag and means for providing an inflation gas. The air bag system is designed to inflate the air bag with the inflation gas when a collision between the vehicle and another object is detected.
Usually, air bags are made of a woven fabric to provide strength to the air bag, so that the air bag can withstand the force of an inflation gas quickly inflating the air bag. In addition, some air bags are coated with a composition that can increase or alter the strength, heat resistance, and/or air permeability characteristics of the air bag.
Airbags as supplementary restraint devices for passengers in vehicles have, for example, historically been produced from woven fabrics formed from warp and weft fibers or yarns. The warp and weft fibers or yarns used to form such woven airbags have typically been predominantly nylon 6,6 with filament counts between 34 to 250. Airbag fabrics, including coated fabrics, woven from yarns, including flat yarns, have been described, for example, in U.S. Pat. Nos. 5,508,073; 5,881,776; 6,632,753; and 6,803,333, and in U.S. Published Patent Application Nos. 2006/0284403 and 2007/0031621.
Airbags have also been manufactured using a continuous film of, for example, polyamide or polyurethane. Life Hightech Co Ltd, for instance, markets airbags based on polyurethane films. Using a film for airbags offers the possibility of weight reduction and eliminates the process steps of weaving and finishing. However, the disadvantage of using a continuous film is generally the relatively low resistance to tear propagation exhibited by films. For this reason, designs for film-based airbags frequently employ a tear resistant reinforcing element in combination with the continuous film. Such reinforced film airbags are disclosed, for example, in U.S. Pat. Nos. 5,746,446 and 6,149,194 and in U.S. Published Patent Application Nos. 2006/0192373, 2007/0065614 and 2007/0278775.
Notwithstanding the availability of airbags fashioned from both fabrics and reinforced films, it would be advantageous to provide new substrate materials for airbag construction which impart to airbags made therefrom a combination of desirable properties and characteristics. In particular, such new substrate materials would desirably provide the benefits of using a film, namely the potential for low thickness and high strength, while also providing the benefits of a woven structure, namely high tear strength and good damage tolerance.
In addition to the functional demands of airbag cushions, there are also increasing demands on vehicle manufacturers to reduce the weight and volume of airbag modules. Use of smaller and lighter airbags in airbag modules allows space in the vehicle for other functionalities. Smaller and lighter airbag modules would also potentially reduce the overall vehicle weight, thereby leading to increased fuel efficiency and reduction in CO2 output of the vehicle.